1. Field of the Invention
The present invention relates to a lead terminal to be connected and to hold an electronic component elements, such as, an energy-trap type piezoelectric resonator, and the present invention also relates to an electronic component including such a lead terminal.
2. Description of the Related Art
Conventionally, a lead terminal including a U-shaped cup-like section has been used as a lead terminal and joined to an electronic component device, such as a piezoelectric resonator. An example of this type of lead terminal is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 63-67908.
FIG. 6 illustrates lead terminals each having a U-shaped cup-like section. In lead terminals 51 and 52 shown in FIG. 6, substantially U-shaped cup-like sections 51b and 52b are arranged to extend continuously with and along side ends of corresponding linear lead terminal bodies 51a and 52a. The lead terminal bodies 51a and 52a consist of narrow plate-shaped members. In the structure of the U-shaped cup-like section 51b, a pair of stopper sections 51b, and 51b.sub.2 are arranged to extend continuously beside each other at one end of the U-shaped cup-like section 51b. In the structure of the U-shaped cup-like section 52b, a pair of stopper sections 52b.sub.1 and 52b.sub.2 are arranged to extend continuously beside each other at one end of the U-shaped cup-like section 52b.
The lead terminals 51 and 52 are obtained by punching out plate-shaped, metallic members, and by bending ends of the punched out plate-shaped, metallic members to form the U-shaped cup-like sections 51b and 52b.
As shown in FIG. 7A which is a horizontal sectional view, when the pair of lead terminals 51 and 52 shown in FIG. 6 are used, a piezoelectric resonator 53 is held by inserting the resonator between the U-shaped cup-like sections 51b and 52b. More specifically, one end of the piezoelectric resonator 53 is inserted into and soldered to the U-shaped cup-like section 51b in order to electrically connect the U-shaped cup-like section 51b to one of the electrodes of the piezoelectric resonator 53. Similarly, the other end of the piezoelectric resonator 53 is inserted into the U-shaped cup-like section 52b in order to electrically connect the other electrode of the piezoelectric resonator 53 to the U-shaped cup-like section 52b.
Accordingly, the piezoelectric resonator 53 can be reliably held by the pair of lead terminals 51 and 52. In addition, the electrodes of the piezoelectric resonator 53 can be electrically connected to the corresponding lead terminals 51 and 52.
As shown in FIGS. 7A and 7B, however, when the piezoelectric resonator 53 that is relatively thin, and a piezoelectric resonator 53A that is relatively thick, are used, the distance or space between the pair of lead terminals 51b and 52b must inevitably be changed. In other words, since the space between the lead terminals 51 and 52 varies with the thicknesses of the piezoelectric resonators 53 and 53A, the space between the lead terminals 51 and 52 cannot be made constant without correcting the sizes of the piezoelectric resonators 53 and 53A in the direction of a line connecting the lead terminals 51 and 52. Therefore, in producing the piezoelectric resonator 53 or 53A, the piezoelectric resonator 53 or 53A must be cut out from a mother piezoelectric plate in correspondence with its position between the lead terminals 51 and 52. Consequently, not only is a substrate used with poor efficiency and the steps of producing the piezoelectric resonators 53 and 53A made complicated, but costs are also increased.
The stopper sections 51b.sub.1, 51b.sub.2, 52b.sub.1 and 52b.sub.2 are placed at both sides of the piezoelectric resonator 53 or 53A in the thickness direction thereof, so that the size of a completed piezoelectric resonator component in the thickness direction of the piezoelectric resonator 53 or 53A inevitably becomes much larger. Therefore, the size of the piezoelectric resonator part cannot be reduced.
Wire rods having circular end surfaces, that is, round wire rods, are frequently used for the lead terminals which are attached to various types of electronic component devices such as piezoelectric resonators. Such lead terminals are disclosed in, for example, Japanese Unexamined Patent Application Publication Nos. 7-291344 and 6-251905.
Although round wire rods with various forms such as a round wire rod with a bent section at an intermediate portion thereof have been proposed, rods having a U-shaped cup-like section for holding an electronic component device are not known.